The objective of this study was to assess the oxygen cost of various intensities of steady-state cycling. VO2 (ml·min -1·kg-1) was measured at rest, during unloaded cycling (UL), 20 Watts, 50% (SS50) & 65% (SS65) of peak watts in 40 COPD patients (64 +/- 9 yrs; FEV1/FVC: 48 +/- 17 % predicted; FEV1:36 +/- 14 % predicted) and 28 age-matched healthy controls (CTRL). Despite higher VE (L·min -1) in COPD vs. CTRL (UL: 20.6 +/- 3.4 vs. 15.4 +/- 4.1; 20W: 24.3 +/- 4.5 vs. 17.8 +/- 4.2), VO2 at rest, at UL and 20W was not higher in COPD compared to CTRL. In addition, comparable slope and intercept coefficients for the VO2 vs. Watt relationship were obtained in COPD and CTRL for submaximal cycling of low to moderate intensity. (Abstract shortened by UMI.)

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 172-183). / Cancer magister, the Dungeness crab, occurs in different habitats during its life cycle, habitats which vary widely in the magnitude of salinity and temperature changes. Cancer magister hemocyanin also changes in structure and oxygenation properties during development. The following question was considered in this thesis: what are the effects of environmental salinity and temperature on metabolic rates, ionic and osmotic regulation and hemocyanin oxygen affinity in Q. magister during development. Metabolic rates and hemolYmph ionic and osmotic concentrations were measured in the megalopa, 1st juvenile, 5th juvenile and adult crab eight hours after acute exposure to 100% seawater (=32 ppt), 75% seawater and 50% seawater at both 10°C and 20°C. The oxygen binding properties of the whole hemolymph from these stages in 100% seawater at 10°C was determined. The effects of calcium and magnesium on the oxygen affinity of purified hemocyanin from different stages were also determined. In 100% seawater, routine metabolic rates of the four stages scale with body mass over the size range, 0.05 gm to 500 gm. The Q10 (10°C to 20°C) for the megalopa is higher in 75% seawater and 50% seawater than in 100% seawater. For the 1st juvenile, 5th juvenile and adult the Q10 values (10°C to 20°C) are independent of salinity. The megalopa, 1st juvenile and 5th juvenile are weaker regulators of hemolymph chloride, sodium and osmotic concentrations than the adult. The megalopa and adult, unlike the 1st juvenile and 5th juvenile, strongly regulate hemolymph calcium in reduced salinity. In 100% seawater hemolymph magnesium is significantly higher in the megalopa, 1st juvenile and 5th juvenile than in the adult. The oxygen affinities of whole hemolymph from the four stages are indistinguishable when adjusted for endogenous L-lactate concentrations; the Bohr coefficients are not significantly different among stages. The effect of magnesium on oxygen affinity of purified adult hemocyanin is influenced by proton concentration; the effect of calcium is independent of proton concentration. In 100% seawater, endogenous inorganic ion concentrations in the whole hemolymph of the various stages reduce the intrinsic stage specific differences in hemocyanin oxygen affinity.

Este estudo tem como objetivo o desenvolvimento de um sistema para oximetria de pulso destinado a medir a saturação arterial de oxigênio. A determinação da saturação de oxigênio no sangue é reconhecida mundialmente como padrão de cuidado em anestesiologia, sendo utilizado em diversas aplicações desde tratamentos intensivos em hospitais até cirurgias veterinárias. O sistema de oximetria desenvolvido emprega um sensor de transmitância utilizando LEDs e um fotodetector como componentes principais. O instrumento é composto de um amplificador de transimpedância, circuito de demultiplexação, filtros passa-faixas, amplificador de ganho digitalmente programável e um processador digital de sinais. Os resultados de funcionamento do protótipo foram comparados com um simulador de oximetria de pulso comercial, obtendo-se um coeficiente r = 0,99954 entre os dados de saturação de oxigênio. Medições in vivo obtidas foram comparadas com medições feitas por um oxímetro comercial, atingindo-se diferenças médias de ±1,67% entre os dados de percentagem de saturação pulsátil e ±1,44 batimentos cardíacos para a taxa de batimentos por minuto. Espera-se que este trabalho possa contribuir para melhorar a monitorização de oxigênio aos tecidos do corpo tornando ainda mais comum e acessível o uso da técnica de medição da oximetria de pulso. / The main subject of this research is the development of a measurement system for pulse oximetry in order to determine oxygen arterial saturation. The measurement of blood oxygen saturation is recognized as a world standard in anesthesiology care, being used in intensive care units as well as in veterinary surgery. The developed oximetry system employs a transmittance probe using light emitting diodes and a photo detector as main components. The instrument is also composed by a transimpedance amplifier, demux and sample-and-hold circuits, pass-band filters, digitally controlled amplifier and a digital signal processor. The functioning results of the prototype were confirmed by using a commercial pulse oximeter simulator, obtaining a coefficient r = 0.99954 between the oxygen saturation data. Also, in vivo results obtained were compared with a commercial pulse oximeter showing mean differences of ±1.67% for percentage saturation data and ±1.44 beats per minute for heart rate. It is hoped that this work can help to improve the oxygen monitoring to body tissues and to make pulse oximetry a more common and accessible monitoring technique.

Este estudo tem como objetivo o desenvolvimento de um sistema para oximetria de pulso destinado a medir a saturação arterial de oxigênio. A determinação da saturação de oxigênio no sangue é reconhecida mundialmente como padrão de cuidado em anestesiologia, sendo utilizado em diversas aplicações desde tratamentos intensivos em hospitais até cirurgias veterinárias. O sistema de oximetria desenvolvido emprega um sensor de transmitância utilizando LEDs e um fotodetector como componentes principais. O instrumento é composto de um amplificador de transimpedância, circuito de demultiplexação, filtros passa-faixas, amplificador de ganho digitalmente programável e um processador digital de sinais. Os resultados de funcionamento do protótipo foram comparados com um simulador de oximetria de pulso comercial, obtendo-se um coeficiente r = 0,99954 entre os dados de saturação de oxigênio. Medições in vivo obtidas foram comparadas com medições feitas por um oxímetro comercial, atingindo-se diferenças médias de ±1,67% entre os dados de percentagem de saturação pulsátil e ±1,44 batimentos cardíacos para a taxa de batimentos por minuto. Espera-se que este trabalho possa contribuir para melhorar a monitorização de oxigênio aos tecidos do corpo tornando ainda mais comum e acessível o uso da técnica de medição da oximetria de pulso. / The main subject of this research is the development of a measurement system for pulse oximetry in order to determine oxygen arterial saturation. The measurement of blood oxygen saturation is recognized as a world standard in anesthesiology care, being used in intensive care units as well as in veterinary surgery. The developed oximetry system employs a transmittance probe using light emitting diodes and a photo detector as main components. The instrument is also composed by a transimpedance amplifier, demux and sample-and-hold circuits, pass-band filters, digitally controlled amplifier and a digital signal processor. The functioning results of the prototype were confirmed by using a commercial pulse oximeter simulator, obtaining a coefficient r = 0.99954 between the oxygen saturation data. Also, in vivo results obtained were compared with a commercial pulse oximeter showing mean differences of ±1.67% for percentage saturation data and ±1.44 beats per minute for heart rate. It is hoped that this work can help to improve the oxygen monitoring to body tissues and to make pulse oximetry a more common and accessible monitoring technique.

Two aspects of possible adaptation In cardiovascular performance caused by Increased plasma electrolytes were examined. Cells In anisotonic plasma may either act as osmometers or volume regulate. Blood flow rate Is dependent upon cell viscosity, which in turn is a consequence of cell volume and membrane deform-ability. Cell volume changes which Increase membrane deform-ability will thus potentially extend the limits of dehydration tolerance. It was found in R. catesbeiana and B. marinus that red blood cell Is maintain constant volume during dehydration. Cells in vitro Initially lose water, but then sodium, potassium and water move Into the cell. Cell viscosity within the physiologic range of hematocrits was higher In salt loaded non-regulating cell Is of B. marinus than In regulating isotonic cells.

No description available.

The role oxygen plays in the developing ovarian follicle is of interest not only to the field of developmental biology but also to in-vitro fertilisation (IVF) technologists, as oxygenation of the oocyte is considered to be a potential determinant of oocyte competence. Oxygen transport through the developing ovarian follicle, and practical aspects of the analysis of oxygen in human follicular fluid were investigated in this work. Mathematical modelling of oxygen transport in the pre-antral, and antrallpreovulatory follicle revealed a number of interesting findings, Contrary to previous conclusions (Gosden & Byatt-Smith, 1986), oxygen can reach the oocyte in the small pre-antral follicle. Improved estimates of diffusion coefficients through the granulosa cell layer and the inclusion of fluid voidage in this layer showed that oxygen can also reach the oocyte in large pre-antral follicles. The amount of oxygen that reaches the oocyte in the pre-antral follicle is a function of its size and degree of vascularisation. Symmetrically distributed vascularisation is superior in achieving a well oxygenated follicle. However, the large pre-antral follicle will eventually reach a size beyond which it cannot grow without anoxic regions developing. The size at which this occurs is consistent with the size at which antrum formation is observed in human follicles. The model predicts that the follicle can avoid an anoxic state through antrum formation, and shows that the follicle develops in a way that is consistent with overcoming mass transport limitations. The oxygen status of the follicle during the antrallpre-ovulatory phase of growth requires that the volume of granulosa cells be balanced by the volume of follicular fluid. Further predictions suggest that oocyte respiration becomes sub-maximal at follicular fluid volumes below approximately 4m1, vascularisation levels below 38%, or fluid i dissolved oxygen levels below 5.1 ~01%. These values are consistent with observations in the literature. It was also shown that the measurement of follicular fluid dissolved oxygen levels could provide a simple measure of the respiratory status of the oocyte, and this may be superior to the measurement of follicular vascularisation which requires knowledge of more parameters. Methodology for the analysis of follicular fluid oxygen solubility and diffusivity was developed using a Clark oxygen electrode. Analysis of these parameters showed that they are similar to human plasma, and allowed the predictive uncertainty of the model to be reduced. Experimental studies into the effects of IVF aspiration on follicular fluid were carried out. Aspiration results in significant changes in the properties of follicular fluid. Dissolved oxygen levels rose 5 * 2 vol%, pH increased by 0.04 * 0.01 pH units, and temperature dropped by 7.7 * 1.3 "C. Mathematical modelling of blood contaminated follicular fluid also showed that contamination results in significant changes in the dissolved oxygen of the fluid. This suggests that if the composition of follicular fluid is to be determined (particularly dissolved oxygen), sampling andlor measurement of fluid must take place before the collection vial of the aspiration kit, and blood contamination must be eliminated. Based on this result, the design and testing of devices capable of reliable sampling andlor rneasurement of oxygen levels of follicular fluid was considered. This presents a continuing challenge, including the integration of routine follicular fluid oxygen measurement into clinical practice.

The focus of this field investigation was an analysis of the work demands being placed on South African forestry workers, in particular Chainsaw Operators and Stackers. Working postures, physiological and perceptual responses were assessed on a sample of 58 workers (29 Chainsaw Operators and 29 Stackers) during a ‘normal’ working shift. Body mass was measured before and after work in order to determine dehydration levels. Polar heart rate monitors were fitted to six workers each day over a period of two weeks in order to record ‘working’ heart rates. Fluid and food intake was monitored and recorded during this initial data collection phase. The Rating of Perceived Exertion and Body Discomfort Scales were explained in Zulu, their native language, and workers were asked to rate their perceptions of effort at regular intervals during work, while areas and intensity of body discomfort was obtained on completion of work. After completing a work shift, a 30 minute ‘recovery’ period was given, thereafter a portable ergospirometer, the k4b², was attached to the worker who then participated in a progressive, submaximal step test for the purpose of establishing individual, and group, heart rate-oxygen uptake (HR/VO[subscript 2]) regressions for predicting oxygen uptake from ‘working’ heart rate responses. These procedures were repeated four weeks later following the introduction of a fluid and nutritional supplement during work which was delivered to the workers while they were executing their tasks. The results revealed awkward working postures with a predominance of trunk flexion during all the harvesting tasks; these postures, adopted for long periods during work, are very likely to lead to the development of musculoskeletal injuries. The mean working heart rates were 123.3 bt.min[superscript (-1)] and 117.6 bt.min[superscript (-1)] during chainsaw operations and stacking respectively. During the step test, the mean heart rate and oxygen uptake responses were 127.9 bt.min[superscript (-1)] and 22.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] (Chainsaw Operators) and 116.9 bt.min[superscript (-1)] and 24.0 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] (Stackers), revealing no significant difference between the ‘working’ heart rates and the heart rates recorded during the step test. Physiological responses were analyzed over the full work shift which was divided into four quarters. Heart rate and oxygen uptake were significantly higher during the last half of the Chainsaw Operators’ work shift compared to the first half. Heart rate increased from 120.7 bt.min[superscript (-1)] during the first quarter to 127.4 bt.min[superscript (-1)] during the last quarter of chainsaw operations. Likewise, oxygen uptake increased from 19.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] to 22.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] from the first to the last quarter of work. During stacking the heart rate (mean of 117.6 bt.min[superscript (-1)]) and oxygen uptake (mean of 24.6 ml.kg[superscript (-1)].min[superscript (-1)]) responses remained stable over the duration of the working shift. Workers lost, on average, 2.8% body mass during work while felling and cross-cutting and 3.6% during stacking. This reduced significantly to a loss of 0.4% body mass when re-tested following the introduction of water and food during the work period. Likewise, the energy deficit was significantly improved due to the introduction of a nutritional supplement. Pre-intervention the deficit was 8861.8 kJ (Chainsaw Operators) and 8804.2 kJ (Stackers) while in the post-intervention phase this deficit was reduced by approximately 50% for both groups of workers.

Indiana University-Purdue University Indianapolis (IUPUI) / The endothelium is a single layer of cells lining the arteries and is involved in many physiological reactions which are responsible for vascular tone. Free radicals are important participants in these chemical reactions in the endothelium. Here we quantify free radicals, ex vivo, in biological tissue with continuous wave electron paramagnetic resonance (EPR). In all of the experiments in this thesis, we use a novel EPR spin trapping technique that has been developed for tissue segments. EPR spin trapping is often considered the ‘gold standard’ in reactive oxygen species (ROS) detection because of its sensitivity and non-invasive nature. In all experiments, tissue was placed in physiological saline solution with 190-mM PBN (N-tert-butyl-α-phenylnitrone), 10% by volume dimethyl-sulphoxide (DMSO) for cryopreservation, and incubated in the dark for between 30 minutes up to 2 hours at 37°C while gently being stirred. Tissue and supernatant were then loaded into a syringe and frozen at -80°C until EPR analysis. In our experiments, the EPR spectra were normalized with respect to tissue volume. Conducting experiments at liquid nitrogen temperature leads to some experimental advantages. The freezing of the spin adducts renders them stable over a longer period, which allows ample time to analyze tissue samples for ROS. The dielectric constant of ice is greatly reduced over its liquid counterpart; this property of water enables larger sample volumes to be inserted into the EPR cavity without overloading it and leads to enhanced signal detection. Due to Maxwell-Boltzmann statistics, the population difference goes up as the temperature goes down, so this phenomenon enhances the signal intensity as well. With the ‘gold standard’ assertion in mind, we investigated whether slicing tissue to assay ROS that is commonly used in fluorescence experiments will show more free radical generation than tissue of a similar volume that remains unsliced. Sliced tissue exhibited a 76% increase in ROS generation; this implies that higher ROS concentrations in sliced tissue indicate extraneous ROS generation not associated with the ROS stimulus of interest. We also investigated the role of ROS in chronic flow overload (CFO). Elevation of shear stress that increases production of vascular ROS has not been well investigated. We hypothesize that CFO increases ROS production mediated in part by NADPH oxidase, which leads to endothelial dysfunction. ROS production increased threefold in response to CFO. The endothelium dependent vasorelaxation was compromised in the CFO group. Treatment with apocynin significantly reduced ROS production in the vessel wall, preserved endothelial function, and inhibited expressions of p22/p47phox and NOX2/NOX4. The present data implicate NADPH oxidase produced ROS and eNOS uncoupling in endothelial dysfunction at 1 wk of CFO. In further work, a swine right ventricular hypertrophy (RVH) model induced by pulmonary artery (PA) banding was used to study right coronary artery (RCA) endothelial function and ROS level. Endothelial function was compromised in RCA of RVH as attributed to insufficient endothelial nitric oxide synthase cofactor tetrahydrobiopterin. In conclusion, stretch due to outward remodeling of RCA during RVH (at constant wall shear stress), similar to vessel stretch in hypertension, appears to induce ROS elevation, endothelial dysfunction, and an increase in basal tone. Finally, although hypertension-induced vascular stiffness and dysfunction are well established in patients and animal models, we hypothesize that stretch or distension due to hypertension and outward expansion is the cause of endothelial dysfunction mediated by angiotensin II type 1 (AT1) receptor in coronary arteries. The expression and activation of AT1 receptor and the production of ROS were up regulated and endothelial function deteriorated in the RCA. The acute inhibition of AT1 receptor and NADPH oxidase partially restored the endothelial function. Stretch or distension activates the AT1 receptor which mediates ROS production; this collectively leads to endothelial dysfunction in coronary arteries.

Indiana University-Purdue University Indianapolis (IUPUI) / Photoacoustic Imaging is a non-invasive optical imaging modality used to image biological tissues. In this method, a pulsating laser illuminates a region of tissues to be imaged, which then generates an acoustic wave due to thermal volume expansion. This wave is then sensed using an acoustic sensor such as a piezoelectric transducer and the resultant signal is converted into an imaging using the back projection algorithm. Since different types of tissues have different photo-acoustic properties, this imaging modality can be used for imaging different types of tissues and bodily organ systems. This study aims at quantifying the process of light conversion into the acoustic signal. Light travels through tissues and gets attenuated (scattered or absorbed) or reflected depending on the optical properties of the tissues. The process of light propagation through tissues is studied using Monte Carlo simulation software which predicts the propagation of light through tissues of various shapes and with different optical properties. This simulation gives the resultant energy distribution due to light absorption and scattering on a voxel by voxel basis. The Monte Carlo code alone is not sufficient to validate the photon propagation. The success of the Monte Carlo code depends on accurate prediction of the optical properties of the tissues. It also depends on accurately depicting tissue boundaries and thus the resolution of the imaging space. Hence, a validation algorithm has been designed so as to recover the optical properties of the tissues which are imaged and to successfully validate the simulation results. The accuracy of the validation code is studied for various optical properties and boundary conditions. The results are then compared and validated with real time images obtained from the photoacoustic scanner. The various parameters for the successful validation of Monte Carlo method are studied and presented. This study is then validated using the algorithm to study the conversion of light to sound. Thus it is a significant step in the quantification of the photoacoustic effect so as to accurately predict tissue properties.